Because of the relation between the acid-base metabolism of the dental plaque and dental caries and periodontal disease formation, studies will be carried out to identify the components of saliva involved in its regulation. We have isolated and synthesized one such substance, a peptide called pH-rise factor. Isotopically and non-isotopically labelled forms will be used to elucidate its mode of action, determine its metabolic fate and examine its enhancing effects on the carbohydrate metabolism of salivary sediment, dental plaque and pure cultures of oral streptococci. Gel filtration techniques developed in our laboratory will be used in conjunction with high voltage electrophoresis, to isolate from mixed and duct saliva (i) the component(s) involved in salivary enhancement of ureolytic activity, and (ii) the peptides and proteins in saliva involved in the formation from amino acids, of base at acidic pH and acid at alkaline pH. The involvement of oxygen in these processes will also be examined. The peptides isolated will be identified and sequenced prior to synthesis for study of their role in these functions. The source of these peptides in cannulated parotid and submandibular salivas will be examined. Using an oxygen probe (0.5 mm diameter) and compatible oxygraph constructed in our laboratory, the PO2 in various intra-oral sites and in resting and stimulated saliva will be determined in order to relate O2 levels in plaques to that available from saliva. Using pure cultures of oral streptococci the role of the above in the regulation of their acid-base metabolisms will be examined. This aspect will attempt to determine the contribution of streptococcal metabolism to that of the mixed floras of salivary sediment and dental plaque. Finally, other bacterial components of plaque will be examined for their influence on the pH as preliminary to development of ways for manipulating flora composition. BIBLIOGRAPHIC REFERENCES: Korayem, M.R. and Kleinberg, I. Effect of pH on oxygen uptake during lactic and amino acid utilization by the salivary sediment microflora. J. Dent. Res. 53, 90, 1974.